Storage racks are widely used in industrial and commercial settings. In these settings, it is desirable to maximize the space offered by these racks. This is accomplished by placing pallets or boxes close to each other, oftentimes such that they occupy the entire shelf space, leaving little or no space between the pallets or boxes. This practice can make the stored boxes or pallets especially susceptible to fire damage.
In a typical setting where storage racks are used, such as a warehouse, smoke detectors and overhead sprinkler systems are commonly employed as fire safety and containment systems. Several factors can affect the effectiveness of these systems. For example, to maximize the effectiveness of the sprinkler system in containing a fire, the fire needs to reach the sprinkler heads as quickly as possible in order to extinguish the fire before it builds up too much heat and intensity. Similarly, the benefits of smoke detectors can best be utilized if smoke triggers the detectors in the early stages of a fire. Additionally, water from the overhead sprinkler system needs to freely flow through the shelves to contain a fire that has broken out at any shelving level and to prevent it from spreading to other storage racks. When stored goods are closely and tightly spaced on a shelf, the effectiveness of the fire safety and containment systems are reduced because smoke cannot rise, fire cannot dissipate, and water cannot freely flow to the fire. This is particularly problematic in storage facilities that store large numbers of boxes because boxes can be packed together to form a relatively tight seal against rising smoke and descending water.
Efforts have been made to address this problem. In certain storage environments, fire codes require the surface area of each shelf to have a certain amount of open area—generally fifty percent of the surface area. These open areas serve two primary purposes. First, the open areas allow a fire that has broken out on a lower rack level to travel upwards and to release heat in the process. Thus, the fire progresses upwards towards overhead sprinklers to activate the sprinklers, rather than laterally through the rack. Second, the open areas of each shelf allow water from the overhead sprinkler system to flow downward to the lower rack levels once the fire has been detected. One system that meets these fire code regulations is described in U.S. Pat. No. 6,401,944 to Kircher et al. entitled “Storage Rack Shelving,” and U.S. Pat No. 7,156,243 to Henning et al. entitled “Perforated Decking,” which are incorporated herein by reference. Kircher et al. discloses a corrugated deck for use as shelving with a plurality of apertures forming open areas comprising fifty percent of the surface area of each deck.
While the fifty percent open area regulation provides a useful mechanism to address fire safety and containment, some fire codes, such as foreign fire codes, may not require shelves with a fifty percent open area in all storage environments. In some storage environments, a lower percentage of open area may be allowed, while in others, there may be no requirement for open areas in the shelves.
Another system that has been employed to address the fire safety issue in storage racks is the use of vertical flue spaces. Flue spaces are gaps or openings left in the storage rack structure that form a vertical passage that allows fires to spread vertically to the sprinklers and water to flow down to lower rack levels. The sizes and locations of such flue spaces are typically dictated by local or national fire codes, fire protection standards and/or insurance requirements. there are two common types of flue space: “transverse” flue spaces, which are usually located at every rack upright and are perpendicular to the rack rows (i.e., they extend from the front of the shelving space to the back of the shelving space); and “longitudinal” flue spaces, which run parallel to the rack rows, and may be located between back-to-back rows or may even be formed by aisles between the racks. Typical flue spaces are required to be six inches wide, and fire inspectors and codes often allow the space between the rack uprights to form a portion of this width.
While flue spaces are commonly required, they are typically provided by simply stacking the boxes or other stored goods towards one upright, leaving the required flue space at the other end. This is shown in FIGS. 1A-1C, which illustrate top and front views of a typical set of storage racks, and an isometric view of a similar storage rack. In FIGS 1A-1B, there are two racks 102, which are positioned back-to-back with an aisle 104 on either side. Each rack 102 includes a number of vertical uprights 106 that support horizontal crossbars 108. As shown in FIG. 1C, typical uprights have front faces 118 having “teardrop” holes 120, and lateral faces 122 that have square holes 124. Shelves 110 are mounted on the crossbars 108 between each set of uprights 106 to form separate storage spaces 111 on the racks 102. Boxes 112 or other stored goods are stored within the storage spaces 111. As shown, in common practice, a transverse flue space 114 is formed within each storage space 111 by simply stacking the boxes 112 towards one end of the storage space 111. This leaves a transverse flue space having width “w,” which, as shown, is partially formed by the gap between the uprights 106. To promote proper box stacking, the shelves 110 may extend only up to the edge of the desired flue space 114, making it more difficult to obstruct the flue space 114. In fact, when rack manufacturers are informed of the size of the articles being stored, they often size the racks to fit a specific number of articles, but leave a sufficiently wide transverse flue space.
In addition to transverse flue spaces, the storage racks 102 may have a longitudinal flue space 116 formed between them. In some cases, wires, straps or meshes have been stretched between adjacent rear uprights 106 to prevent boxes or other goods from extending into this longitudinal flue space. Such attempts to maintain the longitudinal flue space have been marginally successful because such devices tend to bend or buckle when boxes are pressed against them.
While the foregoing flue space system is simple and inexpensive, it suffers from a number of problems. Primarily, it is not uncommon for boxes to be positioned to partially or fully obstruct the flue space. Furthermore, even when the boxes are properly stacked, they can deform over time and ultimately lean into, and possibly obstruct, the flue space.
Some efforts have been made to address these problems. One such effort is described in U.S. Pat. No. 5,160,294 to Petter entitled “Spacer Rack for Smoke Detection,” which is incorporated herein by reference. Petter discloses an open wire mesh column that extends from the front to the back of a pallet storage rack to create a vertical passageway through which smoke can travel. However, the Petter system suffers from a number of shortcomings. For example, the Petter system is large and bulky. The size and complexity of the system makes it difficult to implement. In addition, the system must be set up on an empty storage rack. Thus, the Petter system would either have to be set up prior to using the storage rack or after emptying the items already on the storage rack in order to retrofit those racks. Additionally, the Petter system requires the wire mesh columns to penetrate through each shelving layer to form the passageway. Thus, the system would require extensive modification of the storage rack shelves where storage racks with continuous shelves are used.
It is believed that another effort to address the problem with conventional flue spaces provided relatively complex welded crossbars that were mounted to the front face of each front upright (i.e., the surface facing the aisle 104), and the rear face of each rear upright (i.e., the surface facing the longitudinal flue space 116). In addition to being relatively difficult to manufacture, and thus expensive, it is understood that these crossbars were difficult to install on a common rack system, particularly where the rack was already loaded with boxes or other goods.
Therefore a need still exists for an economical and functional flue spacer system that will address the fire safety issue in storage racks and allow retrofitting to filled storage racks.